378 E. Hitchcock on the Metamorphism of 
be identieal as to geological age; yet we incline rather to the 
opinion, that, quartz rocks, micaceous and talcose schist and 
gneiss, may be varieties of the same original rock, which meta- 
morphism has sometimes converted into one and sometimes into 
others of the series. Quartz rock may be the residuum of certain 
silicates; the schists and gneiss are these silicates modified; any 
of these rocks, we think, might be formed out of the conglome- 
rate under consideration, as we shall now endeavor to show. 
so, we might perhaps find it in connection with them all, without 
implying a difference of age. 
In the NE. part of Wallingford, Vt.,on the western slope of the Green 
Mts. on the hill north of David Hager’s, is an interesting exhibition of 
the conglomerate. Numerous bowlders are scattered over the fields, 
which are instruetive, but the embossed ledge half a mile north of Hager’s 
is most so. It has been rounded and smoothed by the drift agency so as 
to show the pebbles and their alteration with the schists, very distinctly, 
as the following sketch of a portion of the ledge, taken by A. D. Hager, 
my assistant in the geological survey of Vermont, will evince. It will be 
seen that the schist often containing small pebbles or coarse grains of 
sand, is interstratified somewhat irregularly with the pebbles; just as we 
often see in the alluvial deposits, and in the sandstones that have not 
been metamorphosed. The drift strize are quite distinct upon it, running 
southeasterly, as shown on the sketch, fig. 3. 
‘West. ‘ 
ro strike of these strata is about N.E. and S.W. and the dip 70° W., 
t it i e i 
sometimes rises to 90° near by. To show its position in re- 
Spect to a micaceous quartz approaching micaceous schist, on the 
upper side, and to the Green mountain gneiss below it, we give the ad- 
joining sketch, Fig. 4. These rocks constitute a single massive ledge, 
P 
